Hyperspectral remote sensing of aquatic ecosystems: first experiences with EnMAP and updates on PRISMA

Hyperspectral remote sensing techniques for assessing bio-physical parameters and processes inland and coastal waters have been developed for more than three decades. Overall, the availability of a continuous spectrum makes algorithms more effective in a wide variety of waters with varying water column depths and bottom reflectance, and lead to a more successful retrieval of a larger number of properties. In such a context, spaceborne imaging spectroscopy is providing a valuable tool for a synoptic continuous monitoring at local to global scale. This technology is advancing rapidly and new missions have been developed in recent years. In 2019 only, the Japanese HISUI, the Chinese ZY1E AHSI and the Italian PRISMA have been placed on orbit while, more recently, the EnMAP joint the hyperspectral sensor satellite fleet to support research and applications in several domains (e.g., agriculture, raw materials, atmosphere, inland and coastal waters, snow, forestry). This study shows some preliminary investigation of hyperspectral data acquired by most recent satellites, as EnMap but also PRISMA. Examples of water reflectance obtained by EnMAP images acquired in aquatic ecosystems encompassing different gradients of water turbidity, trophic status, deep and shallow waters are presented to outline the capabilities of the sensor for aquatic ecosystems. The comparisons of EnMAP with in situ reference measurements will be presented while the synergic use of EnMap with other missions (e.g. PRISMA, Sentinel-2) is discussed for water resources monitoring as well as to support the development of new missions, such as CHIME.